Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front elevation view of a first embodiment of a display screen or portion thereof with transitional graphical user interface, showing a first image thereof;

FIG. 2 is a second image thereof;

FIG. 3 is a front elevation view of a second embodiment of a display screen or portion thereof with transitional graphical user interface, showing a first image thereof; and,

FIG. 4 is a second image thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-2 and FIGS. 3-4. The process or period in which one image transitions to another image forms no part of the claimed design.

The outermost broken lines in the figures show a display screen, are for informational purposes only and, form no part of the claimed design. The other broken lines in the figures show portions of the graphical user interface that form no part of the claimed design.

The drawing is lined for color. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 